Method for correcting SOC of energy storage battery

Abstract

The invention belongs to the technical field of energy storage batteries, and particularly relates to a method for correcting the SOC of an energy storage battery, which comprises the following steps: a detection unit calculates the SOC of the energy storage battery according to the received open-circuit voltage information of the energy storage battery from an energy storage battery management system and the OCV-SOC curve information of the energy storage battery stored in the detection unit; evaluating the accuracy of the estimated residual electric quantity interval corresponding to the current open-circuit voltage value of the energy storage battery; if the evaluation result is qualified, the detection unit obtains the SOC correction value of the energy storage battery according to the estimated residual electric quantity interval; if the evaluation result is unqualified, the detection unit calculates the SOC correction value of the energy storage battery according to the received open-circuit voltage information, working voltage information and working current information of the energy storage battery from the energy storage battery management system and the internal resistance-SOC curve information corresponding to each open-circuit voltage value stored in the detection unit; and the detection unit controls the energy storage battery management system to correct the SOC of the energy storage battery according to the obtained SOC correction value.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage batteries, and in particular relates to a method for correcting the SOC of an energy storage battery. Background Art

[0002] Energy storage batteries are an essential component of smart grids, renewable energy access, distributed power generation, microgrid systems, etc. Lithium-ion batteries have become the mainstream energy storage batteries due to their advantages such as high energy density, high conversion efficiency, fast response speed, high charge retention rate, long cycle life and no memory. When the energy storage system is running, the battery status needs to be monitored and managed to ensure its safety and reliability throughout its life cycle. SOC is an important parameter of the battery status, so the accuracy of SOC estimation is very important.

[0003] Energy storage lithium-ion battery SOC estimation methods include discharge method, open circuit voltage method, electrochemical impedance method, ampere-hour integration method, neural network and Kalman filter method. Among them, the ampere-hour integration method has become a commonly used SOC estimation method due to its advantages such as simplicity, reliability and strong versatility. However, long-term use of the ampere-hour integration method to estimate the battery SOC will lead to an increasing SOC deviation, so the SOC needs to be corrected regularly. Because the open circuit voltage of the battery can be measured and the testing cost is low, the open circuit voltage method is a commonly used energy storage battery SOC correction method. The open circuit voltage method is used to correct the SOC of the energy storage battery. Usually, after the energy storage battery is left to stand for a certain period of time, the open circuit voltage of the energy storage battery is obtained at this time. The SOC correction value of the energy storage battery at this time is obtained through the OCV-SOC curve of the energy storage battery and the open circuit voltage of the energy storage battery, and then the energy storage battery management system is controlled according to the obtained SOC correction value to correct the SOC of the energy storage battery.

[0004] However, since the OCV-SOC curve of the energy storage battery usually has a platform interval (that is, the interval in the OCV-SOC curve where the corresponding open circuit voltage changes less as the remaining power of the energy storage battery changes), and the energy storage battery management system is limited to the detection accuracy of the open circuit voltage of the energy storage battery (usually 1 millivolt), when the open circuit voltage method is used alone as the correction method for the SOC of the energy storage battery, when the measured open circuit voltage is in the platform interval, the SOC estimation range of the energy storage battery obtained according to the OCV-SOC curve is large (usually causing the difference between the maximum and minimum values ​​of the SOC estimation range to be greater than 1%, and even greater than 5% in some cases). When the SOC correction value of the energy storage battery is calculated according to the SOC estimation range, there will be a large calculation error of the obtained SOC correction value, which will further affect the technical problem of the correction accuracy of the SOC of the energy storage battery. Summary of the invention

[0005] The present invention provides a method for correcting the SOC of an energy storage battery, thereby solving the technical problem in the prior art that when the open circuit voltage method is used alone as the method for correcting the SOC of the energy storage battery, when the measured open circuit voltage is in a platform range, a large calculation error of the obtained SOC correction value occurs, thereby affecting the correction accuracy of the SOC of the energy storage battery.

[0006] The technical solution adopted by the present invention is: a method for correcting the SOC of an energy storage battery, comprising:

[0007] The detection unit evaluates the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery according to the open circuit voltage information of the energy storage battery received from the energy storage battery management system and the OCV-SOC curve information of the energy storage battery stored in the detection unit;

[0008] If the evaluation result of the accuracy of the estimated remaining power interval is qualified, the detection unit obtains the SOC correction value of the energy storage battery according to the estimated remaining power interval;

[0009] If the evaluation result of the accuracy of the estimated remaining power interval is unqualified, the detection unit calculates the SOC correction value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information of the energy storage battery received from the energy storage battery management system, and the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit;

[0010] The detection unit controls the energy storage battery management system to correct the SOC of the energy storage battery according to the obtained SOC correction value.

[0011] The detection unit is used to evaluate the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery according to the open circuit voltage information of the energy storage battery received from the energy storage battery management system and the OCV-SOC curve information of the energy storage battery stored in the detection unit; when the evaluation result of the accuracy of the estimated remaining power interval is qualified (that is, when the measured open circuit voltage is not in the platform interval), the SOC of the energy storage battery is corrected by simply using the open circuit voltage method; and when the evaluation result of the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), the detection unit is used to correct the SOC of the energy storage battery according to the open circuit voltage information received from the energy storage battery management system. The system manages the open circuit voltage information, the operating voltage information and the operating current information of the energy storage battery, and the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit, to calculate the SOC correction value of the energy storage battery; when the evaluation result of the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), an accurate SOC correction value can also be obtained, which solves the technical problem in the prior art that when the open circuit voltage method is used alone as the SOC correction method of the energy storage battery, when the measured open circuit voltage is in the platform interval, the calculation error of the obtained SOC correction value is large, thereby affecting the correction accuracy of the SOC of the energy storage battery.

[0012] The platform interval is finely divided into domains (that is, each domain includes an open circuit voltage in the platform interval and a corresponding estimated remaining power interval), and the relationship between the battery internal resistance and SOC is analyzed in each domain (based on the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit), and the corresponding SOC correction value can be obtained by calculating the internal resistance of the energy storage battery.

[0013] Furthermore, the method for evaluating the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery includes:

[0014] The detection unit obtains the current open circuit voltage value of the energy storage battery according to the open circuit voltage information;

[0015] The detection unit obtains the estimated remaining power interval corresponding to the open circuit voltage value according to the obtained open circuit voltage value and the OCV-SOC curve information stored in the detection unit;

[0016] If the difference between the maximum and minimum values ​​of the estimated remaining power interval is not greater than a preset value, the detection unit's evaluation result of the accuracy of the estimated remaining power interval is qualified; otherwise, the detection unit's evaluation result of the accuracy of the estimated remaining power interval is unqualified.

[0017] Furthermore, the preset value ranges from 1% to 2%.

[0018] Furthermore, the method in which the detection unit calculates the SOC correction value of the energy storage battery according to the open circuit voltage information, the operating voltage information, the operating current information and the internal resistance-SOC curve information includes:

[0019] The detection unit calculates the current internal resistance value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information;

[0020] The detection unit obtains an estimated SOC value of the energy storage battery according to the open circuit voltage information, the internal resistance-SOC curve information, and the obtained current internal resistance value;

[0021] The detection unit obtains the SOC correction value according to the obtained SOC estimation value.

[0022] Furthermore, the detection unit uses the obtained SOC estimation value as the SOC correction value.

[0023] In another technical solution, if the evaluation result of the accuracy of the estimated remaining power interval is unqualified, the detection unit calculates the SOC correction value of the energy storage battery based on the remaining power information, open circuit voltage information, operating voltage information and operating current information of the energy storage battery received from the energy storage battery management system, and the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit.

[0024] Further, the method for the detection unit to calculate the SOC correction value of the energy storage battery according to the remaining power information, the open circuit voltage information, the operating voltage information, the operating current information and the internal resistance-SOC curve information includes:

[0025] The detection unit calculates the current internal resistance value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information; and obtains the current remaining power value of the energy storage battery according to the remaining power information;

[0026] The detection unit obtains an estimated SOC value of the energy storage battery according to the open circuit voltage information, the internal resistance-SOC curve information, and the obtained current internal resistance value;

[0027] The detection unit calculates the SOC correction value of the energy storage battery according to the obtained current remaining power value and the SOC estimation value.

[0028] Furthermore, the current internal resistance value is calculated using the following formula:

[0029]

[0030] Among them, R is the current internal resistance value of the energy storage battery; U1 is the current open circuit voltage value of the energy storage battery; U2 is the current operating voltage value of the energy storage battery; I is the current operating current value of the energy storage battery.

[0031] Furthermore, the method for the detection unit to calculate the SOC correction value of the energy storage battery according to the obtained current remaining power value and the SOC estimated value includes:

[0032] The current remaining power value is used as a priori value, the SOC estimation value is used as an observation value, and the SOC correction value is calculated using the Kalman filter method.

[0033] By calculating the current internal resistance of the energy storage battery when the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), combining the internal resistance-SOC curve information corresponding to the measured open circuit voltage, obtaining the SOC estimation value, and using the Kalman filter method to calculate the SOC correction value, the correction accuracy of the SOC of the energy storage battery can be further improved.

[0034] Furthermore, if the evaluation result of the accuracy of the estimated remaining power interval is qualified, the detection unit uses the average value of the maximum value and the minimum value of the estimated remaining power interval as the SOC correction value of the energy storage battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 Flow chart of the method for correcting the SOC of the energy storage battery in the embodiment. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0038] like Figure 1 As shown, this embodiment provides a method for correcting the SOC of an energy storage battery, comprising:

[0039] The detection unit evaluates the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery according to the open circuit voltage information of the energy storage battery received from the energy storage battery management system and the OCV-SOC curve information of the energy storage battery stored in the detection unit;

[0040] If the evaluation result of the accuracy of the estimated remaining power interval is qualified, the detection unit obtains the SOC correction value of the energy storage battery according to the estimated remaining power interval;

[0041] If the evaluation result of the accuracy of the estimated remaining power interval is unqualified, the detection unit calculates the SOC correction value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information of the energy storage battery received from the energy storage battery management system, and the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit;

[0042] The detection unit controls the energy storage battery management system to correct the SOC of the energy storage battery according to the obtained SOC correction value.

[0043] The detection unit is used to evaluate the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery according to the open circuit voltage information of the energy storage battery received from the energy storage battery management system and the OCV-SOC curve information of the energy storage battery stored in the detection unit; when the evaluation result of the accuracy of the estimated remaining power interval is qualified (that is, when the measured open circuit voltage is not in the platform interval), the SOC of the energy storage battery is corrected by simply using the open circuit voltage method; and when the evaluation result of the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), the detection unit is used to correct the SOC of the energy storage battery according to the open circuit voltage information received from the energy storage battery management system. The open circuit voltage information, operating voltage information and operating current information of the energy storage battery, as well as the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit, are used to calculate the SOC correction value of the energy storage battery; when the evaluation result of the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), an accurate SOC correction value can also be obtained, which solves the technical problem in the prior art that when the open circuit voltage method is simply used as the SOC correction method of the energy storage battery, when the measured open circuit voltage is in the platform interval, the calculation error of the obtained SOC correction value is large, thereby affecting the correction accuracy of the SOC of the energy storage battery.

[0044] The platform interval is divided into fine domains (that is, each domain includes an open-circuit voltage in the platform interval and a corresponding estimated remaining power interval), and the relationship between the battery internal resistance and SOC is analyzed in each domain (based on the internal resistance-SOC curve information corresponding to each open-circuit voltage value stored in the detection unit). The corresponding SOC correction value can be obtained by calculating the internal resistance of the energy storage battery.

[0045] In this embodiment, the above OCV-SOC curve information and the internal resistance-SOC curve information corresponding to each open circuit voltage value are obtained by performing a charge and discharge test on the energy storage battery.

[0046] Specifically, in this embodiment, the method for evaluating the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery includes:

[0047] The detection unit obtains the current open circuit voltage value of the energy storage battery according to the open circuit voltage information;

[0048] The detection unit obtains the estimated remaining power interval corresponding to the open circuit voltage value according to the obtained open circuit voltage value and the OCV-SOC curve information stored in the detection unit;

[0049] If the difference between the maximum and minimum values ​​of the estimated remaining power interval is not greater than the preset value, the detection unit's evaluation result of the accuracy of the estimated remaining power interval is qualified; otherwise, the detection unit's evaluation result of the accuracy of the estimated remaining power interval is unqualified.

[0050] Preferably, in this embodiment, the preset value ranges from 1% to 2%.

[0051] In this embodiment, the method for calculating the SOC correction value of the energy storage battery includes multiple schemes.

[0052] Option 1:

[0053] The method for the detection unit to calculate the SOC correction value of the energy storage battery according to the open circuit voltage information, the operating voltage information, the operating current information and the internal resistance-SOC curve information includes:

[0054] The detection unit calculates the current internal resistance value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information;

[0055] The detection unit obtains an estimated SOC value of the energy storage battery according to the open circuit voltage information, the internal resistance-SOC curve information, and the current internal resistance value obtained;

[0056] The detection unit obtains an SOC correction value according to the obtained SOC estimation value.

[0057] Preferably, in solution one, the detection unit uses the obtained SOC estimation value as the SOC correction value.

[0058] Option 2:

[0059] If the evaluation result of the accuracy of the estimated remaining power interval is unqualified, the detection unit calculates the SOC correction value of the energy storage battery based on the remaining power information, open circuit voltage information, operating voltage information and operating current information of the energy storage battery received from the energy storage battery management system, and the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit.

[0060] Specifically, in the second solution, the detection unit calculates the SOC correction value of the energy storage battery according to the remaining power information, the open circuit voltage information, the working voltage information, the working current information and the internal resistance-SOC curve information, including:

[0061] The detection unit calculates the current internal resistance value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information; and obtains the current remaining power value of the energy storage battery according to the remaining power information;

[0062] The detection unit obtains an estimated SOC value of the energy storage battery according to the open circuit voltage information, the internal resistance-SOC curve information, and the current internal resistance value obtained;

[0063] The detection unit calculates the SOC correction value of the energy storage battery according to the obtained current remaining power value and the SOC estimation value.

[0064] Among them, the current internal resistance value is calculated using the following formula:

[0065]

[0066] Among them, R is the current internal resistance value of the energy storage battery; U1 is the current open circuit voltage value of the energy storage battery; U2 is the current operating voltage value of the energy storage battery; I is the current operating current value of the energy storage battery.

[0067] Preferably, in the second solution, the method in which the detection unit calculates the SOC correction value of the energy storage battery according to the obtained current remaining power value and the SOC estimation value includes:

[0068] The current remaining power value is used as the prior value and the SOC estimation value is used as the observation value, and the Kalman filtering method is used to calculate the SOC correction value.

[0069] By calculating the current internal resistance of the energy storage battery when the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), and then combining the internal resistance-SOC curve information corresponding to the measured open circuit voltage to obtain the SOC estimation value, and using the Kalman filter method to calculate the SOC correction value, the correction accuracy of the SOC of the energy storage battery can be further improved.

[0070] Preferably, in this embodiment, if the evaluation result of the accuracy of the estimated remaining power interval is qualified, the detection unit uses the average value of the maximum value and the minimum value of the estimated remaining power interval as the SOC correction value of the energy storage battery.

[0071] The method for correcting the SOC of an energy storage battery provided by the present invention has at least the following technical effects or advantages:

[0072] 1. Using the detection unit, based on the open circuit voltage information of the energy storage battery received from the energy storage battery management system and the OCV-SOC curve information of the energy storage battery stored in the detection unit, the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery is evaluated; when the evaluation result of the accuracy of the estimated remaining power interval is qualified (that is, when the measured open circuit voltage is not in the platform interval), the SOC of the energy storage battery is corrected by simply using the open circuit voltage method; and when the evaluation result of the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), the detection unit is used to receive the information from the energy storage battery management system. The open circuit voltage information, operating voltage information and operating current information of the energy storage battery, as well as the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit, are used to calculate the SOC correction value of the energy storage battery; when the evaluation result of the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), an accurate SOC correction value can also be obtained, which solves the technical problem in the prior art that when the open circuit voltage method is used alone as the SOC correction method of the energy storage battery, when the measured open circuit voltage is in the platform interval, the calculation error of the obtained SOC correction value is large, thereby affecting the correction accuracy of the SOC of the energy storage battery.

[0073] 2. Divide the platform interval into fine domains (that is, each domain includes an open-circuit voltage in the platform interval and a corresponding estimated remaining power interval), and analyze the relationship between the battery internal resistance and SOC in each domain (based on the internal resistance-SOC curve information corresponding to each open-circuit voltage value stored in the detection unit). The corresponding SOC correction value can be obtained by calculating the internal resistance of the energy storage battery.

[0074] 3. When the evaluation result of the accuracy of the estimated remaining power interval is unqualified (that is, when the measured open circuit voltage is in the platform interval), the current internal resistance value of the energy storage battery is calculated, and then the internal resistance-SOC curve information corresponding to the measured open circuit voltage is combined to obtain the SOC estimation value, and the SOC correction value is calculated using the Kalman filter method, which can further improve the correction accuracy of the SOC of the energy storage battery.

[0075] The above are only specific application examples of the present invention and do not constitute any limitation to the protection scope of the present invention. Any technical solutions formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the present invention.

Claims

1. A method for correcting the SOC of an energy storage battery, characterized in that: include: The detection unit evaluates the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery according to the open circuit voltage information of the energy storage battery received from the energy storage battery management system and the OCV-SOC curve information of the energy storage battery stored in the detection unit; If the evaluation result of the accuracy of the estimated remaining power interval is qualified, the detection unit obtains the SOC correction value of the energy storage battery according to the estimated remaining power interval; If the evaluation result of the accuracy of the estimated remaining power interval is unqualified, the detection unit calculates the SOC correction value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information of the energy storage battery received from the energy storage battery management system, and the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit; The detection unit controls the energy storage battery management system to correct the SOC of the energy storage battery according to the obtained SOC correction value.

2. The method for correcting the SOC of the energy storage battery according to claim 1, characterized in that: The method for evaluating the accuracy of the estimated remaining power interval corresponding to the current open circuit voltage value of the energy storage battery includes: The detection unit obtains the current open circuit voltage value of the energy storage battery according to the open circuit voltage information; The detection unit obtains the estimated remaining power interval corresponding to the open circuit voltage value according to the obtained open circuit voltage value and the OCV-SOC curve information stored in the detection unit; If the difference between the maximum and minimum values ​​of the estimated remaining power interval is not greater than a preset value, the detection unit's evaluation result of the accuracy of the estimated remaining power interval is qualified; otherwise, the detection unit's evaluation result of the accuracy of the estimated remaining power interval is unqualified.

3. The method for correcting the SOC of the energy storage battery according to claim 2, characterized in that: The preset value ranges from 1% to 2%.

4. The method for correcting the SOC of the energy storage battery according to claim 1, characterized in that: The method for the detection unit to calculate the SOC correction value of the energy storage battery according to the open circuit voltage information, the operating voltage information, the operating current information and the internal resistance-SOC curve information includes: The detection unit calculates the current internal resistance value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information; The detection unit obtains an estimated SOC value of the energy storage battery according to the open circuit voltage information, the internal resistance-SOC curve information, and the obtained current internal resistance value; The detection unit obtains the SOC correction value according to the obtained SOC estimation value.

5. The method for correcting the SOC of the energy storage battery according to claim 4, characterized in that: The detection unit uses the obtained SOC estimation value as the SOC correction value.

6. The method for correcting the SOC of the energy storage battery according to claim 1, characterized in that: If the evaluation result of the accuracy of the estimated remaining power interval is unqualified, the detection unit calculates the SOC correction value of the energy storage battery based on the remaining power information, open circuit voltage information, operating voltage information and operating current information of the energy storage battery received from the energy storage battery management system, and the internal resistance-SOC curve information corresponding to each open circuit voltage value stored in the detection unit.

7. The method for correcting the SOC of the energy storage battery according to claim 6, characterized in that: The method for the detection unit to calculate the SOC correction value of the energy storage battery according to the remaining power information, the open circuit voltage information, the operating voltage information, the operating current information and the internal resistance-SOC curve information includes: The detection unit calculates the current internal resistance value of the energy storage battery according to the open circuit voltage information, the operating voltage information and the operating current information; and obtains the current remaining power value of the energy storage battery according to the remaining power information; The detection unit obtains an estimated SOC value of the energy storage battery according to the open circuit voltage information, the internal resistance-SOC curve information, and the obtained current internal resistance value; The detection unit calculates the SOC correction value of the energy storage battery according to the obtained current remaining power value and the SOC estimation value.

8. The method for correcting the SOC of the energy storage battery according to claim 7, characterized in that: The current internal resistance value is calculated using the following formula: Among them, R is the current internal resistance value of the energy storage battery; U1 is the current open circuit voltage value of the energy storage battery; U2 is the current operating voltage value of the energy storage battery; I is the current operating current value of the energy storage battery.

9. The method for correcting the SOC of the energy storage battery according to claim 7, characterized in that: The method for the detection unit to calculate the SOC correction value of the energy storage battery according to the obtained current remaining power value and the SOC estimated value includes: The current remaining power value is used as a priori value, the SOC estimation value is used as an observation value, and the SOC correction value is calculated using the Kalman filter method.

10. The method for correcting the SOC of an energy storage battery according to claim 1, characterized in that: If the evaluation result of the accuracy of the estimated remaining power interval is qualified, the detection unit uses the average value of the maximum value and the minimum value of the estimated remaining power interval as the SOC correction value of the energy storage battery.

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